Many modern ophthalmic surgical procedures require an accurate determination of the location of the center of different surfaces in the eye. For example, during certain cataract surgical procedures, such as capsulorhexis, it is necessary to locate the center of the natural eye lens to remove the lens capsule. In cataract surgery, the natural lens is removed and replaced with an artificial intraocular lens (IOL). Due to mechanical and symmetry reasons, the implanted IOL moves to the center of the capsular bag, but the capsular bag is not visible to the surgeon during cataract surgery. Accurate determination of the natural lens location is generally required to allow the surgeon to most efficiently remove the natural lens and properly locate the implanted IOL. This is merely one example of the various ophthalmic procedures which require accurate determination of the center of a particular surface in an eye.
Unfortunately, however, conventional techniques for locating the center of the various surfaces in the eye have limited effectiveness and/or accuracy. For example, some techniques to determine the center of an eye lens use the center of the pupil as an approximation of the eye lens center. But, these techniques have limited accuracy as the geometric center of the lens does not always coincide with center of the dilated pupil.
Therefore, improved techniques for determining the location of the center of different surfaces in the eye are needed.